title: Overexpression of the Escherichia coli TolQ protein leads to a null-FtsN-like division phenotype.
abstract: Mutations involving the Tol-Pal complex of Escherichia coli result in a subtle phenotype in which cells chain when grown under low-salt conditions. Here, the nonpolar deletion of individual genes encoding the cytoplasmic membrane-associated components of the complex (TolQ, TolR, TolA) produced a similar phenotype. Surprisingly, the overexpression of one of these proteins, TolQ, resulted in a much more overt phenotype in which cells occurred as elongated rods coupled in long chains when grown under normal salt conditions. Neither TolR nor TolA overexpression produced a phenotype, nor was the presence of either protein required for the TolQ-dependent phenotype. Consistent with their native membrane topology, the amino-terminal domain of TolQ specifically associated in vivo with the periplasmic domain of FtsN in a cytoplasm-based two-hybrid analysis. Further, the concomitant overexpression of FtsN rescued the TolQ-dependent phenotype, suggesting a model wherein the overexpression of TolQ sequesters FtsN, depleting this essential protein from the divisome during Gram-negative cell division. The role of the Tol-Pal system in division is discussed.
authors.affiliation: Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio, 43403; Division of Science and Math, Lorain County Community College, Elyria, Ohio, 44035.
authors.forename: Mary A
authors.initials: MA
authors.lastname: Teleha
authors.forename: Adam C
authors.initials: AC
authors.lastname: Miller
authors.forename: Ray A
authors.initials: RA
authors.lastname: Larsen
mesh_terms: D002453:Cell Cycle; D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics / Q000502:physiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015870:Gene Expression; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020798:Two-Hybrid System Techniques
chemical_list: D029968:Escherichia coli Proteins; C098711:FtsN protein, E coli; D008565:Membrane Proteins; C060792:tolQ protein, E coli
keywords: Cell division; Escherichia coli; FtsN; TolQ